Use of camera observations for the quantification of coastal morphodynamics on an arctic delta
Abstract
Deltas often occur in the coastal zone of many fjords and open seas in the high-arctic region of north-eastern Greenland. These deltas form the transition between the land and sea and act as temporal sediment traps for terrestrial material. Melt water discharge from glaciers is the main source of sediment towards the delta. Minor sources of sediment transport towards the delta are through reworking of sediments on the delta slope, through lateral transport from the adjacent shores and through stranded sediment-loaded ice out of the fjord. Losses of sediments occur through further transport of sediments by the river on the delta towards the fjord or by reworking of the delta fringes by coastal processes due to ice, waves and tides. Sandy spits and small barriers often fringe the shoreline of a delta. These features are typically formed and active in the ice-free periods when coastal processes by waves and drifting ice rework the delta front and adjacent coastal cliffs. Local sources of sediment on the delta are former glacial deposits close to the active channel. Changes in fluvial channel patterns on deltas have a significant impact on the coastal morphology along its fringes. Lateral channel migration can locally cause cliff erosion and introduce an extra sediment source in the local budget of an active delta plain. Stabilization of channels or even channel lobe switching reduce the fluvial impact on the delta and introduce the formation of beach ridges and spits along the (former) delta edge. These accumulative features are formed in the ice-free summer periods and fed by alongshore sediment input from adjacent shores due to wave-driven alongshore currents, and by the reworking of the sediments on the delta plain by wave-driven cross-shore processes. In this presentation, we focus on the analysis of a long-term (decadal) data set with daily recorded camera images of the Young Sound, a fjord near Zackenberg in Greenland. These images are used to statistically describe the ice-coverage and ice-free periods in the fjords and results are used to quantify the actual coastal evolution of e.g. the spits on the delta platform over the last decade. Besides, we use similar camera images to observe, classify and quantify the extreme river discharge events that frequently occurred at Zackenberg delta during the summer periods in the last years.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFMEP33A0898K
- Keywords:
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- 3020 MARINE GEOLOGY AND GEOPHYSICS / Littoral processes;
- 4217 OCEANOGRAPHY: GENERAL / Coastal processes;
- 4546 OCEANOGRAPHY: PHYSICAL / Nearshore processes;
- 4558 OCEANOGRAPHY: PHYSICAL / Sediment transport